My furnace is 15 years old I tried to turn it on today and the ignitor never heated up nor did gas ever flow to the unit. I tested the ignitor and it works what could the problem be?

The circuit that proves the igniter. I would just replace the whole assembly as it usually goes out at the same time, but keep the parts. DrTom4444

I have a coleman furnace what happens is the burner goes out and just blows cold air could it it be the upper reset switch?

I have a colman gas furnace and the burner keeps going out could it be the upper reset switch

You have to find out why something occurs that shuts off the gas valve from the hi-limit switch. It could be that the fan motor or capacitor is bad, or the fan switch is bad or set wrong. It can also be that the filter is stopped up, or the AC coils are stopped up. Something is keeping the airflow too low for it to trip the hi-limit if it is tripping. You are just going to have to get in there with a meter and find out what is wrong.

I have a York gas furnace it made a clicking noise and started blowing cold air it will not come back on what's wrong?

What kind of meter?

You need a good digital volt/ohm meter (that also does millivolts if you want to check thermocouples, otherwise this feature is not needed.). You can get good ones at Radio Shack for anywhere from $24.99 to more. I have this one and it works great. You absolutely cannot do anything without a meter. Also, here is a manual: http://www.radioshack.com/product/index.jsp?productId=4214667&znt_campaign=Category_CMS&znt_source=CAT&znt_medium=RSCOM&znt_content=CT2032235# (Make sure when meter is on "ohms" you turn off all power to unit and discharge a capacitor before you test it.) http://www.radioshack.com/product/index.jsp?productId=4214667&znt_campaign=Category_CMS&znt_source=CAT&znt_medium=RSCOM&znt_content=CT2032235

I have a York furnace 80 percent it sometime it cycles several times before it will stay going it does everything it should but once its lit it shuts down and repeats the cycle I have tried cleaning the flame sensor with no luck an thoughts ? Thanks tom